The augurscope consists of a tripod-mounted display that can be wheeled to different locations and then rotated and tilted to view a virtual environment that is aligned with the physical background. Video from an onboard camera is embedded into this virtual environment. The augurscope utilises a GPS receiver, electronic compass, accelerometer and rotary encoder to acheive global position tracking at the same time as smooth local interaction. In August 2001 we [researchers] tested an initial application in which the public explored Nottingham's medieval castle from the site of its modern replacement. Analysis of use revealed issues with lighting, movement and relating virtual and physical viewpoints, and showed how environmental factors and physical form affected interaction.